1. Field of the Disclosure
The present invention relates to a liquid crystal display device which is capable of preventing a brightness deterioration in spite of dimming of the backlight unit below 100 percent.
2. Description of the Related Art
As the information society spreads, the requirements for display devices are varied and gradually increasing. In accordance therewith, a variety of display devices such as liquid crystal display (LCD) devices, plasma display panels (PDP), electro-luminescent display (ELD) devices, vacuum fluorescent display (VFD) devices, and so on, have been researched. Furthermore, some display devices already have been applied to many appliances.
More specifically, the LCD devices are rapidly replacing cathode ray tubes (CRTs) and are used most often as a portable image (or picture) display device, because they have features such as superior picture quality, light weight, slimness, low power consumption, and so on. These LCD devices are being developed in a variety of shapes which are applied to computer monitors, television display screens, and so on, as well as to portable notebook computer monitors.
The LCD devices use anisotropic and polarizing characteristics of liquid crystal in order to display an image. It is possible to directionally align liquid crystal molecules because they are thin and long. In accordance therewith, the alignment direction of the liquid crystal molecules can be controlled by an electric filed applied to the liquid crystal.
The LCD devices of the related art can be generally defined into an LCD panel displaying an image (or a picture) and a drive portion applying drive signals to the LCD panel.
The LCD panel includes two substrates combined to form a fixed cell gap and a liquid crystal layer interposed between the two substrates. Any one of these substrates includes gate lines arranged to separate from each other by a fixed distance, data lines perpendicularly arranged to the gate lines and defining pixel regions, and thin film transistors (TFTs) formed in intersecting portions of the gate lines and the data lines. Each of the thin film transistors responds to a scan signal from the gate line and transfer a data signal from the data line to a pixel electrode. Accordingly, the pixel electrodes on the pixel regions sequentially receive the data signals line by line, as the scan signal is sequentially applied to the gate lines, thereby displaying an image (or a picture).
Such LCD devices are mostly driven in a dimming system that applies the data signal to each pixel and simultaneously turns on and off a backlight unit. More specifically, the backlight unit maintains a turning off state before the thin film transistor of any one pixel is turned on, and goes to a turning-on state when the data signal is charged in the one (or the pixel), thereby the LCD device displays one image (or one picture). As a result, the LCD device can prevent a blurring phenomenon.
However, the LCD device with the backlight unit of dimming system has a problem in that the brightness is deteriorated from repeatedly turning on and off its light sources.